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Tunnel through Jointed Rock (Read 2433 times)
Tunnel through Jointed Rock on: April 24, 2024, 03:09:49 pm
I am facing a specific issue with my simulation, where I am simulating tunneling through jointed rock formations.

I have noticed that when the joint intersects directly with the tunnel, the displacements and stresses fail to appear after entering all the necessary simulation parameters. In contrast, when the joint is positioned before and after the tunnel, the simulation behaves as expected, showing all displacements and stresses clearly.

The Script:

ADONIS>> newmodel()
ADONIS>> rect("startPoint",50,50,"endPoint",-50,-50)
ADONIS>> circle("centerPoint",0,0,"radius",6,"numSeg",100)
ADONIS>> joint("startPoint",-10,-50,"endPoint",10,50,"id",1)
ADONIS>> joint("startPoint",-9,-50,"endPoint",11,50,"id",2)
ADONIS>> discretize("size","auto")
ADONIS>> gmsh("size","auto","elemtype","T3","useNMD","on")
ADONIS>> material("create","IsoElastic","matid",1,"matname","Material 1","density",2500,"shear",1.92308e+08,"bulk",4.16667e+08)
ADONIS>> material("create","IsoElastic","matid",2,"matname","Material 2","density",2500,"shear",2.08333e+06,"bulk",2.77778e+06)
ADONIS>> excavate("region",0.74019,0)
ADONIS>> excavate("region",-2.03552,-0.925237)
ADONIS>> excavate("region",1.85047,-1.11028)
ADONIS>> material("assign","matid",1,"region",23.6861,-20.5403)
ADONIS>> material("assign","matid",1,"region",-20.3552,-12.7683)
ADONIS>> material("assign","matid",2,"region",-2.40562,-13.8786)
ADONIS>> material("assign","matid",2,"region",3.33085,15.1739)
ADONIS>> imaterial("edit","ifid",1,"jkn",2e+08,"jks",2e+08)
ADONIS>> imaterial("edit","ifid",2,"jkn",2e+08,"jks",2e+08)
ADONIS>> applybc("xyfix","xlim",-51.628,61.991,"ylim",48.667,52.183)
ADONIS>> applybc("xyfix","xlim",47.002,74.204,"ylim",-56.625,52.924)
ADONIS>> applybc("xyfix","xlim",-65.507,62.916,"ylim",-59.585,-49.223)
ADONIS>> applybc("xyfix","xlim",-51.998,-47.742,"ylim",-56.625,54.219)
ADONIS>> initial("sxx",-2.5e+6)
ADONIS>> initial("syy",-5e+6)
ADONIS>> solve()



Re: Tunnel through Jointed Rock Reply #1 on: April 24, 2024, 04:38:06 pm
Hi,

There is a mistake in your model since you neglected to include the shear strength for your interfaces. For instance, your model will not converge due to excessive displacement along the interface if you set both friction and cohesion to zero.

Please take a look at the attached script file. It adds only 30 degrees of friction, and as a result, the model reaches equilibrium.

Roozbeh



Re: Tunnel through Jointed Rock Reply #2 on: April 25, 2024, 01:44:04 am
Thank you very much, the displacements and stresses clearly show now.

Would you say that if I use the friction for the model where the joints are before and after the tunnel, the results would be more plausible

I have attached the script for the Model where the Joint is before the tunnel.






Re: Tunnel through Jointed Rock Reply #3 on: April 25, 2024, 08:33:04 am
The joint properties are independent of position. Regarding joint shear strength, please review the following references:

https://static.rocscience.cloud/assets/resources/learning/hoek/Practical-Rock-Engineering-Chapter-4-Shear-Strength-of-Discontinuities-Remediated.pdf



Re: Tunnel through Jointed Rock Reply #4 on: April 27, 2024, 06:16:18 am
So just that I Understand right, for the Joint before the tunnel Model I need a different Friction Angle?